Strength properties of aluminum alloys in 115 MPa hydrogen gas

Abstract

Four types of strength tests, slow strain rate tensile (SSRT), fatigue life, fatigue crack growth (FCG) and fracture toughness tests, were performed on six types of aluminum alloys, 5083-O, 6061-T6, 6066-T6, 7N01-T5, 7N01-T6 and 7075-T6, in air and 115 MPa hydrogen gas at room temperature. All the strength properties were not deteriorated in every alloy in 115 MPa hydrogen gas. In all the alloys, FCG rates were lower in 115 MPa hydrogen gas than in air. This was considered to be due to a lack of water- or oxygen-adsorbed film at crack tip in hydrogen gas. Relative reduction of area (RRA) of 5083-O, 6061-T6 and 6066-T6, and fracture toughness of all the alloys were higher in 115 MPa hydrogen gas than in air. These improvements were attributed to a hydrostatic pressure produced in 115 MPa hydrogen gas. RRA of 7N01-T5, 7N01-T6 and 7075-T6, and fatigue life of 6061-T6 in 115 MPa hydrogen gas were almost the same as those in air. These results suggest that aluminum alloy components used in high-pressure hydrogen gas can be designed based on the strength properties in air.

Keywords

• aluminum alloys
• strength properties
• high-pressure hydrogen gas
• hydrostatic pressure
• adsorbed film